Marx sometimes envisioned Capital as a Real God, in the sense that its will is served regardless of the beliefs or individual actions of those in Capitalism, and in that manner sustains "itself" and ensures "its" existence.

Of course, this was based in Materialism, it was always a metaphor.

So then, where is the barrier? Is this an argument based in Moralism, or Materialism? The Proletariat can and must do whatever it can to improve its own conditions, and in the absence of a state that provides for it, this must be done via the Market.

I agree that Workers, especially Marxists, should try to reduce their harmful footprints as much as possible. Boycott union busters and supporters of genocide. However, when it comes to retirement savings, there exist no ethical ways to move forward, except to live entirely off the grid and refuse to use banking systems.

Unfortunately, this can lead to reactionary behavior, a turning back of the clock to an earlier stage of Capitalism. That's why homesteading has a huge fascism problem.

I guess what I am trying to say is that I don't think it's productive to say investing is antithetical to leftism, considering the context. That would be like saying purchasing video games is antithetical to leftism, as they are for personal enjoyment yet support Capitalists. I try to think in terms of Dialectics and what materially benefits the proletariat, and ultimately if it becomes a matter of purity testing I believe we lose sight of the goals of Communism.

I dunno, this became a bit of a ramble. I'll end this with a fun quote:

“The moment anyone started to talk to Marx about morality, he would roar with laughter.”

i really do not understand how you're making that distinction. is it "anything specifically earmarked for retirement" is okay and all other investments beyond that aren't okay? what about college funds for children?

another point: it's perfectly conceivable to invest for the future outside a retirement account and still use those proceeds for survival. What if you need expensive medical treatment in your old age and that's the only way you're able to pay for it?

Depends, are you a believer in means/ends unification a la Anarchism, or are you more of a Marxist? Socialism will not be brought about by personally abstaining from retirement accounts and whatnot, and the State does not provide enough of a welfare net to avoid this issue. Workers must invest to survive, as they must consume products of Capitalism.

Index funds are surprisingly close to market socialism and can be flipped to the benefit of society with little change.

Most employers offer a match on 401(k) contributions. For example, you contribute $500 per paycheck and the employer contributes $250. By turning down this money, you are literally letting the company you work for keep extra money that would otherwise go to you. Fuck companies. Accept the match, so they can’t keep that extra money. You worked for it.

I’m a Marxist and want the downfall of capitalism. However, I’m investing in total market index funds in case capitalism remains the dominant economic system for the rest of my life, because I don’t want to be a wage slave when I’m tired, old woman.

Thanks for explaining. I won't be joining you in the boycott of retirement accounts, but I understand your issue of profiting from other's work.